Canadian Pat. No. 895,398 discloses reacting a mole of an unsaturated hydrocarbon group of 700 to 10,000 mol. wt. with 1 to 1.5 moles of chloro-substituted maleic or fumaric acid, which material can then be further reacted with alcohol.
U.S. Pat. No. 3,215,707 discloses reacting chlorine with a mixture of polyolefin up to 50,000 molecular weight, especially of 250 to 3,000 molecular weight with one or more moles of maleic anhydride depending upon whether one or more succinic anhydride radicals are to be in each polymer molecule.
U.S. Pat. No. 3,927,041 discloses a mole of polybutene of 300 to 3,000 mol. wt. containing 5 to 200 ppm 1,3-di- bromo-5,5-dialkylhydantoin as a catalyst reacted with 0.8 to 5, generally 1.05 to 1.15 moles of dicarboxylic acid or anhydride, to form materials which can be used per se, or as esters, amides, imides, amidines, in petroleum products.
U.S. Pat. No. 4,062,786 in Example 13 shows a polyisobutenylsuccinic anhydride of molecular weight of about 1300 and a Saponification Number of about 100.
U.S. Pat. Nos. 4,113,639 and 4,116,876 disclose an example of alkenyl succinic anhydride having a molecular weight of the alkenyl group of 1300 and a Saponification Number of 103 (about 1.3 succinic anhydride units per hydrocarbon molecule. This alkenyl succinic anhydride may be reacted with polyamine and then boric acid (U.S. Pat. No. 4,113,639), or may be reacted with an amino alcohol to form an oxazoline (U.S. Pat. No. 4,116,876) which is then borated by reaction with boric acid.
U.S. Pat. No. 4,123,373 in Example 3 shows a polyisobutenylsuccinic anhydride of about 1400 molecular weight having a Saponification Number of 80.
U.S. Pat. No. 4,234,435 discloses as oil additives, polyalkene substituted dicarboxylic acids derived from polyalkenes having a M.sub.n of 1300 to 5,000 and containing at least 1.3 dicarboxylic acid groups per polyalkene.
Further related prior disclosures, which are expressly incorporated herein by reference in their entirety are U.S. Pat. Nos. 3,087,936; 3,131,150; 3,154,560; 3,172,892; 3,198,736; 3,219,666; 3,231,587; 3,235,484; 3,269,946; 3,272,743; 3,272,746; 3,278,550; 3,284,409; 3,284,410; 3,288,714; 3,403,102; 3,562,159; 3,576,743; 3,632,510; 3,836,470; 3,836,471; 3,838,050; 3,838,052; 3,879,308; 3,912,764; 3,927,041; Re. 26,330; 4,110,349; 4,113,639; 4,151,173; 4,195,976; and U.K. Pat. Nos. 1,368,277 and 1,398,008.
U.S. Pat. No. 3,401,118 discloses mixed alkenyl succinimides prepared by reacting a polyisobutenyl succinic anhydride (M.sub.n 850-1200 PIB group) with an equal molar quantity of tetraethylene-pentamine and reacting the products so obtained with a lower molecular weight polyisobutenyl succinic anhydride M.sub.n 400-750 PIB group). Each polyisobutenyl succinic anhydride is prepared by conventional methods, and mol ratios of polybutene to maleic anhydride of from 1:1 to 1:10. The proportions of the above higher molecular weight polyisobutenyl succinic anhydrides is disclosed to vary from about 50 to about 98 mol percent.
In Ser. No. 754,001, filed July 11, 1985, oil soluble dispersant additives are disclosed wherein polyolefins of 1500 to 5000 number average molecular weight are substituted with 1.05 to 1.25 dicarboxylic acid producing moieties per polyolefin molecule. Such materials, with a functionality below 1.25:1, have been observed to minimize viscosity interaction with other additives while achieving an effective additive. The composition therein described represents an improvement in that the hydrocarbon polymer required to maintain the oil solubility of the dispersant during engine operation can be provided with fewer acylating units per polyamine. For example, a typical dispersant derived from a polybutene acylating agent with a functionality of 1.3 or more dicarboxylic acid groups per polymer, condensed with a polyethyleneamine containing 4-7 nitrogen atoms per molecule, would require two or more acylating units per polyamine to provide sufficient oil solubility for adequate dispersancy in gasoline and diesel engines. Reducing the functionality below 1.25 generates the requisite ratio of oil-soluble polymer per polyamine at a lower relative stoichiometry of acylating agent per polyamine. Thus, a dispersant derived from a polybutene acylating agent with a functionality of 1.05 condensed with a 5-nitrogen polyethyleneamine in a ratio of 1.5 to 1 contains approximately the same ratio of non-polar to polar groupings as a dispersant made from a polybutene acylating agent with a functionality of 1.4 condensed with the same polyamine in a ratio of 2:1. The former composition would be considerably lower in viscosity and exhibit reduced interactions relative to the latter.
Ser. No. 919,395, filed Oct. 16, 1986 relates to dispersant materials having improved effectiveness as dispersants coupled with enhanced low temperature properties. These inventive materials are particularly useful with V.I. improvers in formulating multigrade oils.
Multigrade lubricating oils typically are identified by two numbers such as 10W30, 5W30 etc. The first number in the multigrade designation is associated with a maximum low temperature (e.g. -20.degree. C.) viscosity requirement for that multigrade oil as measured typically by a cold cranking simulator (CCS) under high shear, while the second number in the multigrade designation is associated with a minimum high temperature (e.g. 100.degree. C.) viscosity requirement. Thus, each particular multigrade oil must simultaneously meet both strict low and high temperature viscosity requirements in order to qualify for a given multigrade oil designation. Such requirements are set e.g., by ASTM specifications. By "low temperature" as used herein is meant temperatures of typically from about -30.degree. to about -5.degree. C. By "high temperature" as used herein is meant temperatures of typically at least about 100.degree. C.
The minimum high temperature viscosity requirement, e.g. at 100.degree. C., is intended to prevent the oil from thinning out too much during engine operation which can lead to excessive wear and increased oil consumption. The maximum low temperature viscosity requirement is intended to facilitate engine starting in cold weather and to ensure pumpability, i.e., the cold oil should readily flow or slump into the well for the oil pump, otherwise the engine can be damaged due to insufficient lubrication.
In formulating an oil which efficiently meets both low and high temperature viscosity requirements, the formulator may use a single oil of desired viscosity or a blend of two lubricating oils of different viscosities, in conjunction with manipulating the identity and amount of additives that must be present to achieve the overall target properties of a particular multigrade oil including its viscosity requirements.
The natural viscosity characteristic of a lubricating oil is typically expressed by the neutral number of the oil (e.g. S150N) with a higher neutral number being associated with a higher natural viscosity at a given temperature. In some instances the formulator will find it desirable to blend oils of two different neutral numbers, and hence viscosities, to achieve an oil having a viscosity intermediate between the viscosity of the components of the oil blend. Thus, the neutral number designation provides the formulator with a simple way to achieve a desired base oil of predictable viscosity. Unfortunately, merely blending oils of different viscosity characteristics does not meet the desired low and high temperature viscosity requirements. However, increasing the proportion of low viscosity oils in a blend can in turn lead to a new set of limitations on the formulator, as lower viscosity base oils are considerably less desirable in diesel engine use than the heavier, more viscous oils.
Further complicating the formulator's task is the effect that dispersant additives can have on the viscosity characteristics of multigrade oils. Dispersants are frequently present in quality oils such as multigrade oils, together with the V.I. improver. The primary function of a dispersant is to maintain oil insolubles, resulting from oxidation during use, in suspension in the oil thus preventing sludge flocculation and precipitation. Consequently, the amount of dispersant employed is dictated and controlled by the effectiveness of the material for achieving its dispersant function. A typical 10W30 U.S. Service Station commercial oil contains from 3 to 4 times as much dispersant as V.I. improver (as measured by the respective dispersant and V.I. improver active ingredients). In addition to dispersancy, conventional dispersants can also increase the low and high temperature viscosity characteristics o a base oil simply by virtue of its polymeric nature. In contrast to the V.I. improver, the dispersant molecule is much smaller. Consequently, the dispersant is much less shear sensitive, thereby contributing more to the low temperature CCS viscosity (relative to its contribution to the high temperature viscosity of the base oil) than a V.I. improver. Moreover, the smaller dispersant molecule contributes much less to the high temperature viscosity of the base oil than the V.I. improver. Thus, the magnitude of the low temperature viscosity increase induced by the dispersant can exceed the low temperature viscosity increase induced by the V.I. imp rover without the benefit of a proportionately greater increase in high temperature viscosity as obtained from a V.I. improver. Consequently, as the dispersant induced low temperature viscosity increase causes the low temperature viscosity of the oil to approach the maximum low temperature viscosity limit, the more difficult it is to introduce a sufficient amount of V.I. improver effective to meet the high temperature viscosity requirement and still meet the low temperature viscosity requirement. The formulator is thereby once again forced to shift to the undesirable expedient of using higher proportions of low viscosity oil to permit addition of the requisite amount of V.I. improver without exceeding the low temperature viscosity limit.
The dispersants of Ser. No. 919,935 were observed to possess inherent characteristics such that they contribute considerably less to low temperature viscosity increases than dispersants of the prior art while achieving similar high temperature viscosity increases. Moreover, as the concentration of dispersant in the base oil is increased, this beneficial low temperature viscosity effect becomes increasingly more pronounced relative to conventional dispersants. This advantage is especially significant for high quality heavy duty diesel oils which typically require high concentrations of dispersant additive. Furthermore, these improved viscosity properties facilitate the use of V.I. improvers in forming multigrade oils spanning a wider viscosity requirement range, such as 5W30 oils, due to the overall effect of lower viscosity increase at low temperatures while maintaining the desired viscosity at high temperatures as compared to the other dispersants. More significantly, these viscometric properties also permit the use of higher viscosity base oils with attendant advantages in engine performances. The high level of functionality combined with the low molecular weight of 700 to 1200 of the olefin polymer component, results in said improved viscometric properties relative to either higher molecular weight polymer or to products with a lower degree of functionality.
Even further improvements, i.e. reductions, in low temperatures CCS viscosity are achieved by increasing the branching of the dispersant molecule in conjunction with control of the hydrocarbyl:polar group ratio. Increased branching is achieved by reacting the hydrocarbyl, substituted dicarboxylic acid or anhydride with a nucleophilic reactant having at least three acid reactive functional groups, e.g. amine, alcohol and mixtures thereof; and controlling the molar ratio of the acid or anhydride containing reactive moiety and nucleophilic reactant within defined limits as specified herein. In the dispersants of Ser. No. 919,935, as the degree of functionality of the nucleophilic reactant increases, this permits more than two hydrocarbyl substituted diacids or anhydride moieties to react therewith, thereby increasing the degree of branching of the resultant product and lowering the CCS viscosity thereof for a given high temperature viscosity. Furthermore, the lower molecular weight of the polymers results in easier handling of the concentrate relative to high molecular weight, high functionality systems which tend to be gel-like.